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PYTHON
!!!PYTHON
NAME
SYNOPSIS
DESCRIPTION
COMMAND LINE OPTIONS
INTERPRETER INTERFACE
FILES AND DIRECTORIES
ENVIRONMENT VARIABLES
AUTHOR
INTERNET RESOURCES
LICENSING
----
!!NAME


python - an interpreted, interactive, object-oriented programming language
!!SYNOPSIS


__python__ [[ __-d__ ] [[ __-E__ ] [[ __-h__ ] [[
__-i__ ] [[ __-O__ ]
[[ __-Q__ ''argument'' ] [[ __-S__ ] [[ __-t__ ] [[
__-u__ ] [[ __-U__ ]
[[ __-v__ ] [[ __-V__ ] [[ __-W__ ''argument'' ] [[
__-x__ ]
[[ __-c__ ''command'' | ''script'' | - ] [[
''arguments'' ]
!!DESCRIPTION


Python is an interpreted, interactive, object-oriented
programming language that combines remarkable power with
very clear syntax. For an introduction to programming in
Python you are referred to the Python Tutorial. The Python
Library Reference documents built-in and standard types,
constants, functions and modules. Finally, the Python
Reference Manual describes the syntax and semantics of the
core language in (perhaps too) much detail. (These documents
may be located via the __INTERNET RESOURCES__ below; they
may be installed on your system as well.)


Python's basic power can be extended with your own modules
written in C or C++. On most systems such modules may be
dynamically loaded. Python is also adaptable as an extension
language for existing applications. See the internal
documentation for hints.


Documentation for installed Python modules and packages can
be viewed by running the __pydoc__ program.
!!COMMAND LINE OPTIONS


__-c__ ''command''


Specify the command to execute (see next section). This
terminates the option list (following options are passed as
arguments to the command).


__-d__


Turn on parser debugging output (for wizards only, depending
on compilation options).


__-E__


Ignore environment variables like PYTHONPATH and PYTHONHOME
that modify the behavior of the interpreter.


__-h__


Prints the usage for the interpreter executable and
exits.


__-i__


When a script is passed as first argument or the __-c__
option is used, enter interactive mode after executing the
script or the command. It does not read the $PYTHONSTARTUP
file. This can be useful to inspect global variables or a
stack trace when a script raises an exception.


__-O__


Turn on basic optimizations. This changes the filename
extension for compiled (bytecode) files from ''.pyc'' to
''.pyo''. Given twice, causes docstrings to be
discarded.


__-Q__ ''argument''


Division control; see PEP 238. The argument must be one of


__-S__


Disable the import of the module ''site'' and the
site-dependent manipulations of ''sys.path'' that it
entails.


__-t__


Issue a warning when a source file mixes tabs and spaces for
indentation in a way that makes it depend on the worth of a
tab expressed in spaces. Issue an error when the option is
given twice.


__-u__


Force stdin, stdout and stderr to be totally
unbuffered.


__-v__


Print a message each time a module is initialized, showing
the place (filename or built-in module) from which it is
loaded. When given twice, print a message for each file that
is checked for when searching for a module. Also provides
information on module cleanup at exit.


__-V__


Prints the Python version number of the executable and
exits.


__-W__ ''argument''


Warning control. Python sometimes prints warning message to
''sys.stderr''. A typical warning message has the
following form: ''file''__:__''line''__:__
''category''__:__ ''message.'' By default, each
warning is printed once for each source line where it
occurs. This option controls how often warnings are printed.
Multiple __-W__ options may be given; when a warning
matches more than one option, the action for the last
matching option is performed. Invalid __-W__ options are
ignored (a warning message is printed about invalid options
when the first warning is issued). Warnings can also be
controlled from within a Python program using the
''warnings'' module.


The simplest form of ''argument'' is one of the following
''action'' strings (or a unique abbreviation):
__ignore__ to ignore all warnings; __default__ to
explicitly request the default behavior (printing each
warning once per source line); __all__ to print a warning
each time it occurs (this may generate many messages if a
warning is triggered repeatedly for the same source line,
such as inside a loop); __module__ to print each warning
only only the first time it occurs in each module;
__once__ to print each warning only the first time it
occurs in the program; or __error__ to raise an exception
instead of printing a warning message.


The full form of ''argument'' is
''action''__:__''message''__:__''category''__:__''module''__:__''line.''
Here, ''action'' is as explained above but only applies
to messages that match the remaining fields. Empty fields
match all values; trailing empty fields may be omitted. The
''message'' field matches the start of the warning
message printed; this match is case-insensitive. The
''category'' field matches the warning category. This
must be a class name; the match test whether the actual
warning category of the message is a subclass of the
specified warning category. The full class name must be
given. The ''module'' field matches the (fully-qualified)
module name; this match is case-sensitive. The ''line''
field matches the line number, where zero matches all line
numbers and is thus equivalent to an omitted line
number.


__-x__


Skip the first line of the source. This is intended for a
DOS specific hack only. Warning: the line numbers in error
messages will be off by one!
!!INTERPRETER INTERFACE


The interpreter interface resembles that of the UNIX shell:
when called with standard input connected to a tty device,
it prompts for commands and executes them until an EOF is
read; when called with a file name argument or with a file
as standard input, it reads and executes a ''script''
from that file; when called with __-c__ ''command,''
it executes the Python statement(s) given as ''command.''
Here ''command'' may contain multiple statements
separated by newlines. Leading whitespace is significant in
Python statements! In non-interactive mode, the entire input
is parsed befored it is executed.


If available, the script name and additional arguments
thereafter are passed to the script in the Python variable
''sys.argv ,'' which is a list of strings (you must first
''import sys'' to be able to access it). If no script
name is given, ''sys.argv[[0]'' is an empty string; if
__-c__ is used, ''sys.argv[[0]'' contains the string
'''-c'.'' Note that options interpreted by the Python
interpreter itself are not placed in
''sys.argv.''


In interactive mode, the primary prompt is `
sys.ps1'' or ''sys.ps2.'' The interpreter quits
when it reads an EOF at a prompt. When an unhandled
exception occurs, a stack trace is printed and control
returns to the primary prompt; in non-interactive mode, the
interpreter exits after printing the stack trace. The
interrupt signal raises the ''KeyboardInterrupt''
exception; other UNIX signals are not caught (except that
SIGPIPE is sometimes ignored, in favor of the ''IOError''
exception). Error messages are written to
stderr.
!!FILES AND DIRECTORIES


These are subject to difference depending on local
installation conventions; ${prefix} and ${exec_prefix} are
installation-dependent and should be interpreted as for GNU
software; they may be the same. The default for both is
''/usr/local''.


''${exec_prefix}/bin/python''


Recommended location of the interpreter.


''${prefix}/lib/python''
${exec_prefix}/lib/python''


Recommended locations of the directories containing the
standard modules.


''${prefix}/include/python''
${exec_prefix}/include/python''


Recommended locations of the directories containing the
include files needed for developing Python extensions and
embedding the interpreter.


''~/.pythonrc.py''


User-specific initialization file loaded by the ''user''
module; not used by default or by most
applications.
!!ENVIRONMENT VARIABLES


PYTHONHOME


Change the location of the standard Python libraries. By
default, the libraries are searched in
${prefix}/lib/python
/usr/local''. When $PYTHONHOME is
set to a single directory, its value replaces both ${prefix}
and ${exec_prefix}. To specify different values for these,
set $PYTHONHOME to ${prefix}:${exec_prefix}.


PYTHONPATH


Augments the default search path for module files. The
format is the same as the shell's $PATH: one or more
directory pathnames separated by colons. Non-existant
directories are silently ignored. The default search path is
installation dependent, but generally begins with
${prefix}/lib/python
sys.path .''


PYTHONSTARTUP


If this is the name of a readable file, the Python commands
in that file are executed before the first prompt is
displayed in interactive mode. The file is executed in the
same name space where interactive commands are executed so
that objects defined or imported in it can be used without
qualification in the interactive session. You can also
change the prompts ''sys.ps1'' and ''sys.ps2'' in this
file.


PYTHONY2K


Set this to a non-empty string to cause the ''time''
module to require dates specified as strings to include
4-digit years, otherwise 2-digit years are converted based
on rules described in the ''time'' module
documnetation.


PYTHONOPTIMIZE


If this is set to a non-empty string it is equivalent to
specifying the __-O__ option. If set to an integer, it is
equivalent to specifying __-O__ multiple
times.


PYTHONDEBUG


If this is set to a non-empty string it is equivalent to
specifying the __-d__ option. If set to an integer, it is
equivalent to specifying __-d__ multiple
times.


PYTHONINSPECT


If this is set to a non-empty string it is equivalent to
specifying the __-i__ option.


PYTHONUNBUFFERED


If this is set to a non-empty string it is equivalent to
specifying the __-u__ option.


PYTHONVERBOSE


If this is set to a non-empty string it is equivalent to
specifying the __-v__ option. If set to an integer, it is
equivalent to specifying __-v__ multiple
times.
!!AUTHOR


Guido van Rossum
E-mail: guido@python.org
And a cast of thousands.
!!INTERNET RESOURCES


Main website: http://www.python.org/
Documentation: http://www.python.org/doc/
Community website: http://starship.python.net/
Developer resources:
http://sourceforge.net/project/python/
FTP: ftp://ftp.python.org/pub/python/
Module repository: http://www.vex.net/parnassus/
Newsgroups: comp.lang.python,
comp.lang.python.announce
!!LICENSING


Python is distributed under an Open Source license. See the
file
----
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